Answer:
a biologic trade of sperm/ semen and egg cells
when these are traded only then reproduction occurs
Answer: b
Explanation:
All the smaller molecules are made up of the organic elements
Answer:
alveoli
Explanation:
They are the smallest structures in our lungs where capillaries exchange O2 and CO2 in blood.
its d . electron because it has a negative charge of however many there are that are circling the atom
